Configuration File

In order to successfully perform the extraction of a transmission spectrum, SLOPpy requires a configuration file, written in YAML, for each target.

The configuration file is divided in several sections:

pipeline and plots

Here the user can list which analysis modules need to be executed (e.g., sky_correction, master_out) and which plots to be shown, respectively. Each data reduction step is accompanied by a plotting module with the same name, so that checking the outcome of each reduction step is straightforward. It is important to remember that analyses and plots are performed independently, that is to say, the user can modify the list of plots anytime without the need of performing the time-consuming analysis again, even for intermediate steps.

nights

Assuming that during a night only one transit of a given target can be observed, in this section the characteristics of each dataset gathered during a night are detailed, such as the lists of all spectra, in_transit spectra, full_transit spectra and out-of-transit (out_transit) spectra, the instrument used to gather the observations (e.g, HARPS, HARPS-N), the kind of mask used for the calibration, and the time of mid-transit in BJD (time_of_transit). If some residuals are still present after telluric correction,, the user can decide to execute an additional correction by setting the keyword spline_residuals equal to True.

Note

It is possible to analyzed data obtained during the same night by two independent instruments, however some night-specific parameters (as the time of transit) will be treated independently. To do so, just use two different labels for the nights.

master-out

In this section the user should set the wavelength_range and the wavelength_step (in Ångström), and the binning_factor (e.g., 20) of the master-out. In addition, the user can decide whether or not to use the composite master-out (e.g., use_composite: False), which is obtained by combining all the master-out spectra of the various nights analyzed.

### instruments In this section the instrument properties, such as the resolution, the number of echelle orders (i.e., red_ccd or blue_ccd) and the wavelength range for the rescaling (wavelength_rescaling), are listed. The path to the archive where the spectra to be analyzed are located (data_archive) is also listed here.

spectral_lines

In this section the spectral lines to analyze are listed (e.g., Na, Halpha).

For each line the user should indicate: the spectral range over which to calculate the transmission spectrum (it must be wide enough to contain both the stellar lines and the continuum); the wavelength [Å] of the spectral lines to analyze; the width of the central passbands around each spectral line for the calculation of the relative absorption depth (AD) in Å (e.g., c075: 0.750); the left/blue (B) and right/red (R) reference bands for the calculation of the relative AD; the polynomial degree for the normalization of spectra and models.

The fit_parameters and the sampler_parameters for the Markov chain Monte Carlo (MCMC) analysis to fit the transmission spectrum are also listed in this section. Here, the user should set the number of steps and walkers (n_step and n_walkers respectively), the range where to compute the fit, the binning step (bin_step) and the parameters priors. Besides, there is a flag to decide whether to leave free the effective planet radius scale factor (free_Rp) and the radial velocity shift due to the wind (free_winds). If the MCMC analysis is to be performed on several spectral lines at the same time (e.g., the two lines of the sodium doublet or the magnesium triplet), the user can also decide whether the lines should share the same FWHM (shared_fwhm: True) or the same radial velocity shift due to the wind (shared_winds: True).

### planets In this section the planetary parameters are listed: the kind of orbit (‘circular’ if the user assumes e=0); the orbital eccentricity; the orbital period [days]; the RV_semiamplitude of the planet [km/s]; the total_transit_duration (between the first and the fourth contact); the full_transit_duration (between the second and the third contact); the orbital inclination [deg]; the reference_time_of_transit [BJD]; the radius_ratio (ratio of planet radius to stellar radius); the semimajor_axis_ratio (ratio of semi-major axis to stellar radius); the impact_parameter.

### star In this section the stellar parameters are listed: the stellar mass [solar masses]); the stellar radius [solar radii]; the differential rotation rate (alpha); the projected obliquity [deg] (lambda); the projected rotational velocity [km/s] (vsini); the stellar inclination [deg]; the RV_semiamplitude of the star [km/s]; the systemic velocity [km/s] (RV_gamma).